Walker led state school Superintendent Tony Evers, his best known Democratic challenger, by 4 points in a June poll by the Marquette University Law School.

But he trailed Evers by 13 points in a July survey by Marist/NBC and by 7 points in a survey released Monday by Emerson College in Boston. The Marquette poll in July didn't do head-to-head matchups between Walker and his eight Democratic challengers.

Walker has a negative approval rating in the Emerson poll but a narrowly positive one in Marquette’s polling.

All three polls suggest Walker right now is more vulnerable to defeat than Baldwin is. But the polls diverge over how vulnerable the governor is. There is a remarkable spread (17 points) between Walker’s margin in Marquette (up 4) and his margin in Marist (down 13).

Here is a closer look at the latest batch of polling in Wisconsin and where these surveys agree and disagree:

Baldwin

The polls are by and large telling the same story here. The first-term Democratic senator enjoys a healthy lead in surveys by Marquette, Marist and Emerson over each of her potential GOP opponents, Leah Vukmir and Kevin Nicholson.

Baldwin led Vukmir by 9 in Marquette’s June poll, by 17 in the Marist poll and by 14 in the Emerson poll.

She led Nicholson by 11 in the Marquette June poll, by 15 in the Marist poll and by 9 in the Emerson poll.

The July Marquette poll didn't do head-to-head matchups between Baldwin and the Republicans.

While these surveys vary over the size of her lead, they all give Baldwin the upper hand, which is consistent with how non-partisan analysts rate the race and with a midterm election climate that historically favors the party out of power.

The obvious caveats are: the election is more than three months away; we don’t even know yet who her opponent will be; and lots of money is being spent against Baldwin on television.

The polling in the Aug. 14 GOP Senate primary fight is inconclusive. Vukmir led Nicholson by 2 in Marquette’s July poll, trailed him by 3 in the Marist poll and the two were tied in the Emerson poll.

Trump

All three pollsters show President Donald Trump clearly “under water” in Wisconsin, meaning more voters disapprove than approve of his performance in office. The president’s approval rating was 42% in Marquette’s July poll, 36% in the Marist poll, and 41% in the Emerson poll. The Marquette and Emerson polls are roughly in line with national polls on Trump’s approval.

Walker

Here’s where the polling really diverges and where some of the differences in how these polls are conducted come into play. Let’s start with the Marquette poll, which tends to carry the most weight in Wisconsin and has by far the most extensive track record in the state.

In Marquette’s polls, the survey sample (the pool of voters who are interviewed) has been divided pretty evenly this year between Democrats and Republicans. If anything, it has tilted slightly Republican. But historically, Democratic voters have outnumbered Republicans in Wisconsin (and in Marquette's own polling in past years). You would expect that to hold true in a year like this one when signs point to a harsh climate for the GOP.

So, if you think the Marquette sample is “too Republican,” then Walker’s 4-point lead over Evers in Marquette’s June survey looks somewhat inflated.

But the Marist poll raises the opposite question. Democrats outnumber Republicans by 8 points in the Marist sample, which is a bigger Democratic advantage than you would expect in Wisconsin.

So if you think the Marist sample is “too Democratic,” then Evers’ 13-point lead in the Marist poll looks pretty inflated (and not all that credible on its face, given all the accumulated polling data on Walker and the Wisconsin electorate that points to a much closer race).

In the Emerson poll, 54% of the sample is college-educated, which is far higher than the actual share of voters in Wisconsin with a bachelor's or graduate degree. That would seem to have the effect of inflating Evers’ lead in the Emerson poll, since college-educated voters tend to be more Democratic. (For these and other reasons, the Emerson poll has its skeptics in Wisconsin).

So where does that leave the governor’s race? We have polls with different track records, using different methods, looking at different samples of the electorate, telling different stories about Walker’s re-election bid.

The polls agree on one thing with respect to Walker: They all suggest he faces a tougher path to re-election right now than Baldwin does.

But they disagree over how tough. Even the best result for Walker — his 4-point lead over Evers in Marquette’s June poll — is within that poll’s margin of error.

We know from all the polling that Evers is well ahead of other Democrats going into the Aug. 14 primary election. But if Evers wins the primary, we don’t know what public perceptions of him will be after a fierce fall campaign.

We also know from years of polling that voters are deeply polarized and evenly divided over the incumbent governor. In Marquette’s combined 2018 polling, 47.9% of registered voters approve of the job Walker is doing, while 47.1% disapprove.

Is Walker down a few points in his re-election race?

Is he up a few points?

Should the governor still be considered the favorite to win?

Based on his election history, political resources and campaign skills and experience, maybe.

Based on the election climate and the inherent challenges of winning a third term, maybe not.